Method of applying stay bolts



Jan. 15, 1929.l 1,698,892

A. F. PlTKlN METHOD 0F APPLYING STAY Boms Original Filed May 24, 1926 Patented Jan. 15, 1929.

UNITED STATES ARTHUR F. PITKIN, 0F SCHENECTADY, NEW YORK.

METHOD OF APPLYING STAY BOLTS.

Original application filed May 24, 1926, Serial No. 111,172.

My invention relates to methods of applying stay bolts to the shell and lircbox sheets of boilers, and has, for an object, to provide a method which can be rapidly and inexpensively performed, and which will produce a steam tight jointure of great durability and strength.

This application a division of my copending application, hled May 2st, 1926, Ser. No. 111,172.

In the practice 'of my invention, 1 form that section of the bolt which is attached to the tirebox sheet, with a cent-ral tell-tale bore, and an external screw thread. The threaded end of the section is lfirst screwer into a correspondingly threaded opening, formed in the i'irebox inner sheet. A tapered recess is then reained in the end of the bolt to facilitate expanding the bolt into steam tight lit with the wall ofthe opening in the lire box sheet. The tapered recess is limited in lengtlnso that it will terminate intermediate the inner and outer faces of the fire box sheet. This form of construction is adopted for the purpose of ensuring' aI suflicient body of metal, con-v tiguous to the outer surface of the sheet, to efiiciently withstand the sheering stresses, incident to service. The next step of the method is that of inserting' an expanding tool into the tapered recess, and expanding the recessed portion of the bolt into steam tight iit with the wall of the opening. A heading operation is next performed, whereby the end o-f the bolt is upset to provide an annular head or flange that overlies the inner face of the firebox sheet.

The improvement claimed is hereinafter fully set forth.

1n the accompanying' drawing: Figure 1 is a view, partly in vertical section, through a staybolt. and the shell and firebox sheets to which it is attached, the inner end of the bolt being shown with the tapered recess reamed therein, the recessed end being unexpanded; Fig. 2, a side View, in elevation, of the reamcr employed to formt-he tapered recess; Fig. a View, partly in vertical section, of the lower portion of the bolt and the firebox sheet, showing the recessed end after it has been expanded; Fig. 4l, a side view, in elevation, of the expanding tool; Fig. 5, a View, similar to Fig. 3, showing the recessed end after it has been headed; Fig. 6, aside view, in elevation, of the heading tool; Fig. 7, a view, similar to Fig. 3, showing a tapered opening in the Divided and-this application led January 29,

Serial No. 164,634.

lirebox sheet, the recess end of the bolt beine unexpanded. i' In the practice of my invention, referring descriptivcly to the specilic embodiment thereof which is herein exemplified, 1 employ a staybolt structure of the articulated type, comprising a main section, 5, having a socket, 6, formed at its upper end, and a socket. 7, formed at its lower end. The upper socket, 6, is jointed to a ball-shaped head, formed on the lower end of the upper section, 9, which is anchored to the shell sheet. The section, 9, has, preferably, a tapered formation, and is welded, as at 11, or otherwise secured to the edges of the opening in the shell sheet, 10, in which it is seated. The lower socket member, 7, of the main section, 5, of the bolt, is jointed to a ball-shaped head, 12, formed on the upper end of the lower end section, 13. The lower end section is formed with a centrally disposed tell-tale bore, 15, and with an external screw thread. v

In practicing my improved methed, the lower end section, 13, of the bolt, is first screwed into the threaded opening in the firebox sheet. A reaming' tool, 18, is then inserted in the telltale bore, and sufficient metal reamed away to provide the tapered rccess,.16. The object of forming the recess is to facilitate the expansion ofthe lower section into steam tight jointure with the walls of the opening in the irebox sheet. The tapered recess is made of limited length so that it will terminate intermediate the inner and outer faces of the irebox sheet. This is done to ensure a sufiicient thickness of metal in that portion of the lower section of the bolt, contiguous to the outer surface of the irebox sheet, to adapt the bolt to efficiently withstand the sheering stresses, enconnted in service. A special reaming tool, 18, is employed to form the tapered recess. This tool is provided with a stop, 19, adapted to bear on the lirebox sheet when the recess has been reanied to the proper depth, and thus positively prevent the recess being reamed to too great a depth.

After the recess has been reamed, the expanding tool, 20, is inserted therein, and the recessed portion of the bolt is swaged or expanded into steam tight fit with the walls of the opening in the irebox sheet.

The next stepv in the method is that of upsetting the end, 22, of the lower section, 13, of the bolt, to form the annular flange or head,

23, which overlies the inner face of the fireboX sheet. This operation is performed by the heading tool, 21.

A modied method of fastening the staybolt is illustrated in F ig. 7. This method differs from that hereinbefore described, in that the threaded opening in the lirebox sheet is formed with a taper, Haring from the Outer to the inner face of the rebox sheet.

I claim as my invention and desire to secure by Letters Patent:

l. The method of attaching a staybolt to a fireboX sheet, which comprises screwing a threaded end of a staybolt into an opening in the irebox sheet; reaining a tapered recess in said end to a depth limited to dispose the inner end of the recess intermediate the inner and outer faces of the firebox sheet; expanding the recessed portion of the bolt into steam tight lit With the Walls of the opening` in the lirebox sheet; and then upsetting the Walls of the -outer end of the recess, to provide a iange overlying the inner 'ace of the iireboX sheet.

2. The method of attaching a staybolt to a irebox sheet; Which comprises forming a tapered staybolt opening,` in the sheet, the opening Haring from the Aouter to the inner face of the sheet; screwing,- a threaded end of a staybolt into said opening; reami'ng a tapered recess in said litted end to a depth limited to dispose the inner end of the recess intermediate the inner and outer faces of the iirebox sheet; expanding the recessed portion of the bolt into steam tight it With the Walls of the opening; and then upsetting the walls of the outer end of the recess, to pro vide a fiange overlying the inner face of the irebox sheet.

ARTHUR F. PITKIN. 

